1. Technical Field
The present invention relates to an electronic device that includes a first electrode layer, a second electrode layer and an insulating layer which is interposed between the first electrode layer and the second electrode layer, a piezoelectric device, a liquid ejecting head, and manufacturing methods for the electronic device, the piezoelectric device and the liquid ejecting head.
2. Related Art
An electronic device provided with a capacitor, such as a piezoelectric element and the like, in which an insulating layer is interposed between electrodes, has been used in a variety of apparatuses, sensors, or the like. For example, in a liquid ejecting apparatus, the piezoelectric element that is provided in the piezoelectric device, which is a type of the electronic device, is used to eject (discharge) a variety of liquids from a liquid ejecting head. The example of the liquid ejecting apparatus includes an image recording apparatus, such as an ink jet printer or an ink jet plotter. Recently, however, the liquid ejecting apparatus has also been applied to a variety of manufacturing apparatuses by taking advantage of a feature that allows an extremely small amount of liquid to be accurately targeted at a predetermined position. For example, the liquid ejecting apparatus is applied to a display manufacturing apparatus that manufactures a color filter of a liquid crystal display and the like, an electrode forming apparatus that forms an electrode an organic electroluminescent (EL) display, a field emission display (FED), and the like, and a chip manufacturing apparatus that manufactures a biochip (biochemical element). A recording head for the image recording apparatus ejects liquid ink, and a colorant ejecting head for the display manufacturing apparatus ejects solutions of respective colorants of red (R), green (G) and blue (B). In addition, an electrode material ejecting head for the electrode forming apparatus ejects liquid electrode materials, and a bioorganic material ejecting head for the chip manufacturing apparatus ejects solutions of liquid bioorganic materials.
The capacitor is formed by a lower electrode layer that is made of metal, a piezoelectric layer made of a piezoelectric body, such as lead zirconate titanate (PZT) and the like, and an upper electrode layer made of metal being sequentially stacked onto a substrate. Such a capacitor functions as the piezoelectric element, and the capacitor is bent and deformed once an electric field, which is generated due to the potential difference between both electrodes, is imparted between the lower electrode layer and the upper electrode layer. Each of the layers that configure such a piezoelectric element is formed, as in JP-A-2015-99864, for example, by etching being performed after each of the layers of metal or a piezoelectric body is made on the substrate, with a patterned resistant layer being used as a mask.
There are some piezoelectric elements in which one end of the lower electrode layer and one end of the piezoelectric layer are provided so as to extend to the outside of the upper electrode layer, and an end of the piezoelectric element is defined by the one end of the upper electrode layer. In such a configuration, at a time when removing the upper electrode layer that is in the outside of the piezoelectric element by etching, so-called over-etching, in which etching is continuously performed even after an amount that is equal to the thickness of the upper electrode layer has been removed, is performed to avoid a short circuit caused by the upper electrode layer not being completely removed. Accordingly, part of the piezoelectric layer is removed. However, if the part of the piezoelectric layer is removed excessively by the over-etching, damage to a boundary of the one end of the piezoelectric element is likely to occur. It is estimated that such damage can occur even at the end of the capacitor which is formed of a pair of upper and lower electrode layers and an insulating layer interposed therebetween.